Tropical Storm AMANDA (Text)

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TROPICAL STORM AMANDA DISCUSSION NUMBER 23
NWS NATIONAL HURRICANE CENTER MIAMI FL EP012014
200 AM PDT WED MAY 28 2014
A 0457 UTC AMSU pass confirmed that Amanda is a sheared tropical
storm, with the low-level center displaced to the south of the deep
convection due to about 15 kt of southerly shear. The convection
itself increased beginning around 0100 UTC, and now the center is
located beneath the cirrus canopy. The initial intensity is held
at 60 kt based mainly on SAB's Dvorak classification of T3.5/4.0
using a shear pattern.
Modest south to southwesterly shear is expected to continue
affecting Amanda for the next 24-36 hours. The shear could relax
somewhat after 36 hours, but Amanda will have moved into a less
favorable thermodynamic environment by that time. Therefore,
gradual weakening is expected, and Amanda is likely to degenerate to
a remnant low in about 3 days. The NHC official forecast is
unchanged from the previous advisory and is fairly close to the
intensity consensus IVCN.
Fixes based on microwave data indicate that Amanda's center began
meandering and drifting eastward during the past 12 hours. The
initial motion is 050/2 kt, but that estimate is highly uncertain.
The steering pattern around Amanda is complicated at the moment.
An elongated mid-level ridge extends from the Four Corners region
of the U.S. southeastward along the length of Mexico, while a broad
mid-level trough covers much of the area west of the Baja
California peninsula. These features should push Amanda slowly
northeastward during the next 48 hours while the cyclone still has
some vertical coherency. Once it becomes a remnant low, Amanda
will be located in very weak low-level flow and will likely meander
or drift southwestward on days 3 through 5. The new NHC track
forecast is farther east than the previous forecast due to the
relocated initial position. It is not, however, quite as far east
as the GFS, ECMWF, or multi-model consensus TVCE.
FORECAST POSITIONS AND MAX WINDS
INIT 28/0900Z 14.6N 112.4W 60 KT 70 MPH
12H 28/1800Z 15.0N 111.9W 50 KT 60 MPH
24H 29/0600Z 15.8N 110.9W 40 KT 45 MPH
36H 29/1800Z 16.6N 109.9W 35 KT 40 MPH
48H 30/0600Z 17.2N 109.0W 30 KT 35 MPH
72H 31/0600Z 17.5N 109.0W 25 KT 30 MPH...POST-TROP/REMNT LOW
96H 01/0600Z 17.0N 110.0W 20 KT 25 MPH...POST-TROP/REMNT LOW
120H 02/0600Z 16.0N 110.5W 20 KT 25 MPH...POST-TROP/REMNT LOW
$$
Forecaster Berg
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